You guys are really overreacting. What are some examples of these champions that break out of the routine meta and suddenly get nerfed? The only one I can think of that accurately fits this description is Veigar, and that's because he had an ancient kit with an ability that, as I said before, was nothing short of broken (and he is getting buffed again in upcoming patches).
What I see more than anything are just people joking about how "x" will be nerfed because it's seen one successful competitive game. Take a look at the recently nerfed champions and tell me they're not nearly all 100% pick ban champions who were either broken from release or suddenly became incredibly dominant because others got nerfed: Azir (and he's not being picked anymore only because his range and damage were both gutted
bloodlover), Kalista, Rek'sai, Yasuo, Gnar in the former category, and in the lattter you have the likes of Jarvan IV, Janna, Lissandra, Xerath, Ahri, Corki, Zed, all champions who got a slap in the wrist exactly because they were being played almost every single damn game (and they're still very popular).
You guys are talking about Kassadin? That shit is the definition of pick and ban ever since competitive league was a thing. They reworked him and he still went back to the same priority spot as before. They want to keep his ult functional and maintain him as the most mobile champion in the game, but mobility is not something easy to create balance around, so they gut him while considering better options. Make up your mind, do you want to see the same champions every game or do you want the obviously overpowered one to be taken down so something else can have some time in the spotlight?
The only champions I feel were overnerfed for no good reason are Jayce and Syndra. They could've probably used some minor adjustments, but they weren't even that popular to begin with and got considerably larger nerfs than most of the champions I listed above.
Now look at some of the champions that have actually been seeing some competitive play for the first time in ages as a direct result of not only being continuously buffed for the last few patches, but also because Riot nerfed the aforementioned dominant champions, giving other picks some breathing room: Kennen, Sejuani, Hecarim, Viktor, Cassiopeia, Nidalee, Fizz (yes, actually seeing more competitive play than before). Wait, are these actually some of the very same champions that make people go "STUPID RITO WILL NOW NERF MY MAIN" whenever they pop up in a competitive game? Why yes they are. And there's no signs of Riot actually nerfing them (except for Nidalee, who's cancer in the jungle). And I'm not even mentioning the multitude of small buffs coming out every patch for other champions, like Gragas, Skarner, Xin Zhao, Nautilus (in PBE), Zac, Elise, Evellyn, Renekton...
And if any (or most, or even some) newly popular champions are instantly nerfed, care telling me while Graves and Sivir, two surprise "hits" of the new season, have stayed untouched for 4 patches in a row, while being at the top of the ADC food chain?
Tl;dr: Before hopping onto the "Riot is ruining mah game" circlejerk, actually think for a second if what you're saying makes any sense.